Azo dyes for cellulosic fibers



an azo dyestuif for cotton and ability and fastness Patented Jan. 19, 1954 UNITED STATE 'AZO DIES FOR CELLULOSIC FIBERS Ludwiglltichter, Easton, Pa.,

assignor to General {Aniline 8 Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application June 28,1950,

Serial No. 170,950

The present invention relates to azo dyes for cellulosic fibers obtained by diazotizing a Z-naphthylamine disulfonic acid, coupling the same with S-methyl-O-anisidine, and phosgenating the resulting azo dyestuff.

Problems have been presented in providing regenerated cellulose capable of dyeing in bright orange-yellow to orange shades and having satisfactory dischargeto light. The problem of light fastness is particularly aggravated with respect to rayon wherein the-dyed rayon is aftertreated with resins to impart an anticrease finish. It has been found that even if the azo dye selected has satisfactory light fastness prior to crease-proofing, the light fastness becomes impaired by the crease-proofing operation.

It is present practice to produce variegated effects on fabrics byforming the fabrics from different fibers having varying aflinities for different dyes. composed inpa-rt of viscose'rayon, and in part of acetate silk are dyed with a dyestuff of one color having affinity only -;for, theviscose rayon and subsequently with another dyestuif of difierent color having afiinityqonly: for the acetate silk or vice versa. The eifects thus obtained are generally referred. to as estron eifects.

It has been proposed "to produce urea derivativegofazo dyes derived from' diazotized'naphthylamine sulionic acids 'on the l one hand and from methoxylated anilines; suc'h'as o-anisi'dine and S-methyl-o-anisidine on the other hand. The prior dyestuffs, however, when used for dyeing cellulosic fibers such as cotton or regenerated cellulose, have been found to suffer in one or more of the following respects:

1. They stain estron effects.

2. They have inferior affinity for cellulosic fibers.

3. The dyes are produced in inappreciable yields.

4. The dyes yield tan or mustard shades instead of shades of orange.

Thus the urea derivatives from naphthylamine monosulfonic acids on the one hand and oanisidine or S-methyI-o-anisidine on the other hand stain estron effects whereas the urea derivatives from naphthylamine trisulfonic acids and the above coupling components have inferior affinity for cellulosic fibers.

The urea derivatives from l-naphthylamine disulfonic acids and o-anisidine are obtained in no appreciable yields. If the o-anisidine be replaced by -methyl-o-anisidine, either inappre- For instance, fabricsmade from fibers I 4 Claims. (01. 260-175) ciable yields of the dyeare obtained or the dyes produce tan or mustard shades in lieu of a pleasant orange shade. I v The urea derivatives from 2-naphthylaminedisulfoni'c' acids and 'o-anisidine give low yields as well as undesired shades.

It has now been discovered that urea anisidine. These dyes dye cotton andregenen ated cellulose bright orange-yellow to orange. shades distinguished by good dischargeability.

and an excellent light fastness. The dyeings on viscose rayonIwithsuch' dyes remain unimpaired.

as to light fastness even after the dyeinsshave been treated to provide .an anti-crease finish. The dyeings leave estron efiects completely um.

stained.

Such dyes and their preparation constitute. the purposes and objects of the present invention.

f The dyes contemplated herein have the following structural formula: V

' con,

RN=N NH 1. l; OH... I in which R. is 4,8-disulfonaphthy fonaphthylene or 5,7-disulfonaphthylene, the naphthylene radical being linked to the azo bridge in the 2-position. 7 These products are prepared by diazotizing the desired 2-naphthylamine disulfonic acid and coupling it in acid solution with a molecular proportion of fi-methyl-o-anisidine. The resulting monazo dye is transformed into the urea by reacting it with phosgene at a temperature ranging from about 20 to C. in a solution with a pH from slightly acid to slightly alkaline.

The invention is further illustrated by the following examples, but it is to be understood that the invention is not restricted thereto.

Example I 22 grams of 2-naphthylamine-4,8-disulfonic acid are dissolved at room temperature in 250' ml. of water to neutral reaction with about 25 m1. of sodium hydroxide solution (40% weight by volume). To this solution. are added 10.5

derivf atives of azo dyestuffs possessing all of the above prerequisites may be obtain'ed 'by phosgenating the ewe dyestuffs resulting from the diaZotiZa-J. tion of 2 naphthy1amine-4,8-disulfonic acid,-F2-" eiie. a isiii ml. of hydrochloric acid (23 B.). This solution is run while stirring into a mixture of 250 m1. of water, ice, 5 grams of sodium nitrite and 5 m1. of hydrochloric acid (23 B.). 10.4 grams of 5- methyl-o-anisidine are dissolved in a solution of 60 ml. of water containing 7.4 ml. of hydrochloric acid. This "solution of the coupler is run into the diazo solution while the temperature is adjusted to about-10 C. The reaction mixture is bufiered to a pH of 3 to 4 with sodium acetate when coupling is finished.

Phosgene is run into the reaction mixture at a temperature between 20 and zfififlnrwhile maintaining the pH of the mixture between 'I -and 8 by adding about 200 ml. of sodium hydroxide solution (40% weight by volume). The product .is salted out and isolated by filtration. The weight of the dry dye is 45 grams. The dye dves cotton and viscose rayon a bright orangefthe dyeings being very fast to light and having the ability to leave :estron effects completely unstained.

Example II action "to estronefiects are similar to :the dye of Example I.

ExampleIII The procedure'is the same as in Example I excepting that the 2-naphthylamine- 4g8-disulioni'c acid is replaced by an identical amount of '2- naphthylamine-6,8-disulfonic acid. After isolation-and drying, the yield is 37.9 grams. The material dyes cotton and viscose rayon somewhat redder-than the .dye of Example I.

It is to .be emphasized that the utilization of the particular naphthylamine disulfonic acids is critical to the proper fulfillment of the invention. Thus, if the monazo dye which is subsequently phosgenated is derived from Z-naphthylamine-3,6-disulfonic acid on the one hand.and.5- methyl-*o-anisidine n the other hand, the yield of the dye is only 32.5%. It is only when employing the particular naphthylamine-disulfonic acids noted above that all of the prerequisites of the invention are attained.

Various modifications of the invention will occur to personsskilled in this art and I therefore do not intend to be limited in the patent granted except as necessitated by the appended claims.

I claim: 1. Products of the following constitution: 6 O CH:

.TNH CO "S in 0 CH;

B. .The :product I of :the vformula:

|2 The product of the formula HQ|S cone om A 2 j'IlUDWIG RICHTER.

References Cited in "the file "of this patent UNITED STATES PATENTS Number Name Date 935,018 'Gunther et ai. Sept. 28, 1909 999,944 "Zartetal. Aug. 8, 1911 1,538,934 Geller May 26, 1925 FOREIGN BATENTS Number. Country Date 21202 Great Britain.;. of 1910 491,515 switzerland May 7, 1909 

1. PRODUCTS OF THE FOLLOWING CONSTITUTION: 